Method of manufacturing open-end blades



Dec. 5, 1944. u os 2,364,235

METHOD OF MANUFACTURING OPEN-END BLADES Filed Feb. 4, 1944 Fig. 1.

//I \Al 16 15 11 4 Fig. 2.

' g INVENTOR. I

' Patented Dec. 5, 1944 METHOD 'OF MANUFACTURING OPEN-END I BLADES Joseph Muros carnbridge, Mass, assignor to Gil- ,letteSa'fety Razor Company, Boston, 'Mass., a

corporation of'Delaware Application February 4, 1944, Serial No. 521,145

4 Claims.

This invention consists in a new and improved method of manufacturing open-end safety razor blades, that is 'to say, blades having a medial longitudinal slot opening out'through one of the which initial convergence is imparted to the two side portions of the'blade, more particularly to their sharpened-outer edges and incidentally to the longitudinal "slot which separates the sharptransverse end edges of the blade. 5 'ened portions of the blade.

Open-end blades may be employed in safety 'The method of my invention follows the usual razors in whichthe cap and guard members-are preliminary steps employed 'in the commercial detachably associated, but they have the ad'dimanufacture of double-edged blades, whether of tional advantage that th'eyma'y be also presented closed-end or open-end type, that is to say, the by endwise movement in safety razors wherein '10 steps of outlining, hardening and tempering the cap and guard members are connected to blade blanksan'd grinding, stropping and honing permit only a limited separation. the outer edges thereof in parallel relation. I

It has been found that in safety razors of the have discovered, however, that by a series of subtype wherein the blade-is transversely flexed when sequent novel steps I am able to impart to an it is clamped in shaving position, as in the Gil- I open-end blade, produced up to this point by the lette type safety razors, the cutting edges of an conventional steps of commercial manufacture, open-end blade are frequently deflected out of a permanent and resiliently maintained contheir normal parallelrelation. Whereas, the'two vergence 'of its sharpened cutting edges. This is sharpened longitudinal edges may be disposed accomplished in accordance with my invention by accurately in parallel relation when the outline of 0 first contracting the side portions of the blade the blade is initially determined, the two edges at the open-end to less than the initial width of are often found to diverge "toward the open-end the slot and then heating the blade to set its of the blade when the blade is flexed and clamped side portions in the position time determined. in the razor. This is due partly to the fact that The most convenient way of carrying out these the hinge portion at the closed or solid end of steps now known to meis positively to gauge the the blade has a restraining eifect on the two side portions which is entirely absent at the open-end of the'blade. Going more into detail, the si e portions are tied together at the closed end of the blade by a flexible connection which, when curved by the cooperating clamping elements of the razor, causes the cutting edges'of the blade to draw together. However, inasmuch as the side portions of the blade adjacent to its open end are two side portions in contracted condition with their "sharpened edges converging to the desired degree toward theopen end of the blade and then heating the hinge portion of the blade and thereby setting the side portions in the gauged position. Preferably and as herein shown this is effected by contracting the side portions by placing 'gauge'pinsin engagement with shoulders at the contracted open end of the blade and then free and unconnected the free ends are not subheating the hinge portion while the blade is so jected to this drawing-in action. These 'difierengaged. The heating is carefully limited in its ences in structure andbehavior, and possibly intensity "so that'it effects the desired setting of other causes, often result in a departure from the two side portions of the blade, but does not parallelism of the two sharpened cutting edges in destroy the resiliency of thehinge portion of the an open-end blade when finallyclamped in shavblade, that is to say, 'sufiicient residual resiliency ing position. 'Such variation detracts from "the is retained inthe hinge portion to maintain the precision of the assembled razor and pro uces gauged position of th'esid'e portions of the blade irregularities in the edgeexposure of the blade and leave 'them with an effective tendency to that may even become "so excessive as to'b e return to tha'tposition-in opposition to any disdangerous in some cases.

I have improved'the 'structure and operation of open-end razor blades and -eliminateduneven edge exposure by causing the two side portions and thus to compensate for any drawing-in of the other ends of the sharpened edges that may occur from any cause whatever. i

In one aspect the present invention consists in a method of manufacturing open-end blades in turbing or spreading force that en'counterin ordinary use.

These'and other characteristics of my improved method will be best unc'lerstood and appreciated from the following detailed description of a prethe blade might ferred 'mannerof carryingit out'as suggested in gauged position and suggests the heating step; and

Fig. 3 is a similar view of the finished blade.

The blade shown in Fig. 1 may be advantageously manufactured in strip formation, a series of blades being outlined in a strip of thin steel by punching so as to form the two similar side portions I and II, the connecting transverse hinge'l2 and the elongated medial slot l3. The slot I3 extends to the right-hand end edge of the blade and is provided with intermediate enlargements 14, for receiving the blade-locating projections of the razor in which the blade is to be used, and with a central enlargement forming a circular perforation for the passage of the shank of the razor cap. The outline of the blade includes reentrant corners which define elongated unsharpened end portions in the blade, one of these constitutes the solidhinge portion l2 while the slot l3 opens out through the other end. It will be understood that the blade blanks as thus outlined are maintained in strip formation by being connected at their end edges.

The blade strip is now hardened and then drawn to the temper best suited for cutting. Its longitudinal edges are then ground, stropped and honed and thus brought to the keen cutting edge required for shaving. The blades are then separated one from another by breaking on the transverse line of their end edges. The steps above explained are now generally followed in the commercial manufacture of razor blades and from the standpoint of the present invention it is immaterial in what order they occur.

Having produced the tempered and sharpened blade as shown in Fig. 1 its two side portions may be contracted, as suggested in Fig. 2, by engaging the blade in a fixture betweena pair of stop or gauge pins 16 and a pair of stop or gauge pins ll located and arranged to fit the reentrant corner recesses of the blade. The gauge pins I6 are spaced substantially in accordance with the outline of the finished blade, that is to say, they fit the recesses of the blade without in any way modifying its outline. The gauge pins l'l, how.- ever. are located somewhat closer together and accordingly impose a contraction of .006." to .010 in the width of the blade at its open end. The gauge pins l1, therefore, forcibly hold together the two side portions of the blade and impart a convergence to the opposed edges of the slot 13 and to the sharpened outer edges of the b ade. While the blade is held in this. condiion the hinge portion I2 is subjected to heat by being engaged between hot plates-or from any o her source of heat and is heated throughout an area substantially that suggested by the hatching in Fig. 2. The effect of this heating continued for less than half a second is that the blade is set with its side portions in the convergent relation determined accurately and uniformly in each case by the gauge pins I1, and

this setting is-efiected without substantially- .A B, whereA indicates the full initial width ofthe slot and B its contracted width.

The blade thus produced may be presented to a safety razor having a gauge stop slightly wider than the dimension Band in this case the sides of the slot l3 will resiliently hug the faces of the stop and will expand the open-end of the blade sufficiently to bring the cutting edges into exact parallelism. Moreover, the blade by its natural resiliency will tend to resist any force tending to spread the open-end of the blade and will compensate for any lag in contraction that may occur between the two ends of the blade when the blade is flexed transversely between the members of the safety razor in which it is used.

It will be apparent that the novel method of my invention may be carried out without requiring any change whatever in the present commercial manufacture of blades from strip steel and without requiring any modification of the steps of grinding, stropping and honing parallel edges in the blade strip. On the contrary, these steps may be carried out with the full advantage of accuracy and convenience incident to dealing with the straight parallel edges, and these supplemented by the step characterizing my novel method.

Having thus disclosed my invention and described in detail one illustrative manner in which it may be carried out I claim as new and desire to secure by Letters Patent:

1. The method of manufacturing open-end safetyrazor blades, which includes the steps of providing a blade having two side sections separated by a medial longitudinal slot, contracting the slot at the open end of the blade to less than its initial width, and heating the blade to set its side portions in the position thus determined.

2. The method of manufacturing open-end safety razor blades, which includes the steps of providing a blade having two side sections separated by. a central longitudinal slot and connected at one end by a flat hinge portion, contracting the slot at its open end to less than its initial width, heating the hinge portion of the blade and thereby setting its side portions in the position thus determined.

3. The method of manufacturing open-end safety razor blades; which includes the steps of providing a blade having two side sections separated by a central longitudinal slot, sharpened at their outer longitudinal edges and connected at one end by a transverse hinge portion, positively gauging the side portions in contracted condition with their sharpened edges converg-- ing toward the open end of the blade, heating the said hinge portion and thereby setting the side portions of the blade in gauged position.

4. The method of manufacturing double-edged, open-end safety razor blades, which includes the steps of providing a blade having two sharpened side portions separated-by amedial slot, connected at one end by a transverse hinge portion and terminating in unsharpened elongated end portions presenting projecting shoulders, contracting the side portions at theopen end of the blade by gauge pins engaged with the shoulders at that end of the blade, heating the hinge portion while the blade is so gauged and thereby setting the side portions in the contracted position thus determined.

- JOSEPH MUROS. 

